Shell molding



Feb. 9, 1960 T. G. BAKER SHELL MOLDING Filed Sept. 3. 195'? SWW;

Iig -Z E i Q INVENTOR.

Tbeodo re G. Baker EcKHoFF f 51./ ATTORNEY Unitsd States `,Patefflt SHELL MOLDING Theodore G. Baker, Oakland, Calif.

Application September 3, 1957, Serial No. 681,513

1 Claim. (Cl. 22-193) This invention relates to an improvement in the production of shell molds.

The manufacture of a shell mold is well-known, e.g., in accordance with the prior known methods, the cope and drag portions of the mold have been separately formed and thereafter removed from the mold and brought together for sealing. Because of the several handling operations which must be performed, the method is relatively slow and costly. Further, in many instances, molds of the desired accuracy were not produced when the cope and drag were united.

' In accordance with this invention, the cope and drag are formed simultaneously and in the same molding operation. Thereafter, the pattern is removed and the two are joined together while each is still retained on or in the original confining support. When suitably joined into a complete mold, the shell is removed from the confining support and is ready for use.

A further unique, novel and important aspect of this method is that the molding composition is blown into the cavity between the patterns and the contour plate simultaneously from each side of the pattern through the slot existing between the pattern plate and each contour plate. Blowing from the sides at the point of parting between the pattern plate and the contour plates eliminates many problems which are inherent when the molding composition is blown in through holes drilled through either plate. This feature makes it possible to use contour plates which are at a temperature whereat the resin in the composition will set up thermally in a short period of time for the problem of maintaining free passage through a small hole is eliminated.

It is in general the broad object of the present invention to provide an improved method and apparatus for the fashioning of shell molds.

The invention includes other objects and features of advantage, some of which, together with the foregoing, will appear hereinafter wherein the preferred form of apparatus and practice of the invention is disclosed along with the several steps involved in practice of the invention. In the drawing accompanying and forming a part hereof, the Figures 1-5 are schematic representations of a suitable apparatus and the operations which are performed by them, to the end that accurate shell molds may be quickly and inexpensively fashioned.

Figure 6 is a side elevation `of an assembly of the contour plates and pattern plate.

Referring particularly to Figure 1, I have shown the upper and lower portions of a pattern mounted upon a pattern plate, the upper portion being designated at 6, the lower portion at 7, and the pattern plate at 8. The pattern on the plate is mounted in close cooperative relationship and in juxtaposition with two contour plates, the upper contour plate being indicated at 9, and the lower contour plate being indicated at 11. The contour plates are suitably supported on a frame and can be moved by hand, but I prefer to use some automatic mechanism, such 2,923,988 ratenteireb. 9, 1960 Ice as the cylinder'and'the piston mechanisms, generally in- As appears in Figure l, .the pattern mounted upon the pattern plate is mounted in spaced juxtaposition` to the contour plates 9" and 11; preferably, the pattern isv preheated and the contour plates are also at a suitable elevated temperature such that when a suitable shell molding composition (e.g., sand mixed with a suitable thermosetting resin, as is well-known in the art) is introduced, it sets up quckly. The sand-resin mix is blown in with air or other suitable means into the space between each contour plate and the pattern. This is achieved by positioning a nozzle (not shown) over each slot ltlbetween the pattern plate 8 and a juxtaposed contour plate and blowing the molding composition into place. With small patterns, one can blow from only one side, while with larger molds, blowing from both sides may be necessary to ensure a quick, complete fill. Usually, the plates are heated to a temperature between 375 and 575 F., the resin-sand mix setting up usually in a matter of seconds, forming an accurate mold.v

When the sand-resin mix has set up, the contour plates 9 and 11 are moved apart, as is indicated in Figure 2, and the pattern mounted upon the pattern plate is removed. The shell molds remain in contact with their respective supporting contour plates, this being achieved, for example, by providing suitable undercuts in each of the contour plates so that the molds remain in engagement with the contour plates.

A suitable binder, such asa thermosetting resin, is then sprinkled upon the terminal edges and other suitable sur faces 16 of each of the molds and the two contour plates are then moved together so that all non-cavity surfaces of the two molds engage and become uniformly bonded together, as is shown in Figure 3. The upper contour plate is then moved away to expo-se the co-pe (Figure 4), while as a linal step, the shell mold is removed fromthe bottom of the contour plate to provide a completed mold (Figure 5).

From the foregoing, I believe it will be apparent that I have provided a novel, simple and improved method and apparatus for the formation of shell molds. The invention is not limited to use with a sand-thernrosetting res-in composition for it can be used with other molding compositions such as sodium silicate, which sets up irnmediately upon application of carbon dioxide.

I claim:

A method of making a shell mold comprising: mounting a pattern between upper and lower contour plates to leave a space between each of said plates and said pattern; blowing a mixture of sand and a thermosetting resin into the spaces between the pattern and said plates; adjusting the temperature of the plates to between about 375 and 575 F. whereby to set up the resin-sand mixture, moving the contour plates laterally apart while maintaining the shells so formed in contact with said contour plates; removing said pattern from between said shells; applying a bonding material to the non-cavity surfaces of each shell; moving said contour plates laterally toward one another whereby to bring the non-cavity surfaces of said shells together; retaining said contour plates in a juxtaposed position until the non-cavity surfaces of said shells have become bonded to each other and thereafter separat- Iing the shell mold so formed from each of said contour plates.

References Cited in the file of this patent UNITED STATES PATENTS 701,331 Mills Sept. 30, 1902 (Other references on following page) '$9,933,983 'A' f A ,V A "if UNITED STATES PATENTS 154,933 Australia Stpt. l. 1955 Ripplnget APL 19 1910 1,119,225 Fl'all APL 3,--1955- Pattison Sept. 14, 1948 vennerholm Apr. 12, 195s OTHER REFERENCES Ensign Dec, 13, 1955 5 Metal Industry, lune 22, 1956, pages S20-522.

Iron Age, vol. 169, Issue 26, pages Ilz-116, pub. June 26, 1952.

Foundry Trade I oumal, Iun'e`28, 1956, pages $07-$13.

FOREIGN PATENTS Great Britain Sept. 9, 1937 

